Spontaneously hypertensive (SHR), stroke-prone (SHR-SP) and control Wistar Kyoto rats (WKR) were treated with either 3% taurine in their drinking water or tap water. Treatment was started at 4 weeks of age and continued through 14 weeks of age. Taurine treatment significantly retarded the development of hypertension in the SHR-SP. The untreated SHR-SP were found to have significantly reduced content of taurine in the liver and serum. Cysteic and decarboxylase was similar in all three strains.